I found this document which details the rules of driver conduct in Chapter IV.
https://www.fia.com/sites/default/files ... e_2020.pdf
As it pertains to overtaking they say:
"However, manoeuvres liable to hinder other
drivers, such as deliberate crowding of a car
beyond the edge of the track or any other
abnormal change of direction, are strictly
prohibited. Any driver who appears guilty of
any of the above offences will be reported to
Which is fairly ambiguous, but I think for blocking moves such as when you squeeze someone to the edge of the track like Mick did to Mazepin or block someone from overtaking by weaving or by showing someone the wall they say:
"More than one change of direction to defend
a position is not permitted."
"A driver may not leave the track without
So it may actually be legal to defend and not give the other driver a car's width if he is not already side by side. But if the attacking car is already to the outside of the leading car then th leading car must give a car's width there. Interesting.